Electronic biopsy instrument with wiperless position sensors

Abstract

An instrument for removing tissue samples from a tissue mass which automatically penetrates, severs, and removes a tissue portion for examination. The instrument is motor powered, preferably by self-contained rechargeable batteries, and employs electrically actuated stops to control the action of penetration into and retraction from the tissue mass. The tissue penetrating means and severing means includes an inner stylet which penetrates the tissue mass and a hollow outer tube or cannula which surrounds the stylet and serves to sever a sample of tissue. In a preferred form the tissue penetrating end of the stylet is notched so that when the stylet penetrates the tissue mass, a portion of the tissue relaxes in the notched area. After tissue penetration by the stylet, the cannula, having a cutting surface at its distal end, penetrates the tissue and cuts off the tissue portion residing in the notched area of the stylet. The tissue penetrating and severing means are operably connected to a motor powered rotary cam assembly by means of cam followers and the rotary motion of the cam is converted to sequential, linear motion in the tissue penetrating means and severing means. The angular position of a cam is monitored with a pair of optoelectronic sensors, thereby providing position feedback without mechanical wear on the position sensor assembly. Improved action is provided by a cam having an S-curve profile.

What is claimed is: 
     
       1. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula, and means for producing reciprocating motion of said stylet and cannula;   position sensing means for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means, said control means including means responsive to said position sensing means for stopping the motion of said stylet and cannula when said cannula reaches a predefined extended position whereby said cannula and stylet are both extended, when said cannula reaches a predefined retracted position whereby said cannula is retracted and said stylet is extended, and when said stylet reaches a predefined retracted position whereby said cannula and said stylet are both retracted; and   switch means for actuating said electronic control means;   wherein said position sensing means includes first means for detecting when said cannula reaches said predefined extended position and when said stylet reaches said predefined retracted position, and second means for detecting when said cannula reaches said predefined retracted position, said first and second means for detecting comprising first and second wiperless sensors, respectively.   
     
     
       2. The electronic biopsy instrument of claim 1, wherein said position sensing means includes an optoelectronic sensor. 
     
     
       3. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula, and means for producing reciprocating motion of said stylet and cannula;   position sensing means including an optoelectronic sensor for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means, said control means including means responsive to said position sensing means for stopping the motion of said stylet and cannula when said cannula reaches a predefined extended position whereby said cannula and stylet are both extended, when said cannula reaches a predefined retracted position whereby said cannula is retracted and said stylet is extended, and when said stylet reaches a predefined retracted position whereby said cannula and said stylet are both retracted; and   switch means for actuating said electronic control means;   wherein said position sensing means includes first means for detecting when said cannula reaches said predefined extended position and when said stylet reaches said predefined retracted position, and second means for detecting when said cannula reaches said predefined retracted position, said first and second means for detecting comprising first and second optoelectronic sensors, respectively.   
     
     
       4. The electronic biopsy instrument of claim 3, wherein said actuator means includes an electric motor, a drive shaft, and a rotary cam coupled to said drive shaft for translating rotary motion to linear motion, and wherein said position sensing means is responsive to the angular position of said rotary cam, said first and second means for detecting including stationary first and second optoisolators, respectively, and a common slotted disc rotatably coupled to said drive shaft.   
     
     
       5. The electronic biopsy instrument of claim 4, wherein said cam has an S-curve profile. 
     
     
       6. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula;   position sensing means for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means; and   switch means for actuating said electronic control means;   wherein said actuator means includes an electric motor, a drive shaft, and a rotary cam coupled to said drive shaft for translating rotary motion to linear motion,   and wherein said position sensing means includes first and second means for sensing the angular position of said rotary cam, said first and second means including first and second optoelectronic sensors, respectively, first and second, respectively, and a common slotted disc rotatably coupled to said drive shaft.   
     
     
       7. The electronic biopsy instrument of claim 6, wherein said cam has an S-curve profile. 
     
     
       8. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula, and means for producing reciprocating motion of said stylet and cannula;   position, sensing means for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means, said control means including means responsive to said position sensing means for stopping the motion of said stylet and cannula when said cannula reaches a predefined extended position whereby said cannula and stylet are both extended, when said cannula reaches a predefined retracted position, whereby said cannula is retracted and said stylet is extended, and when said stylet reaches a predefined retracted position whereby said cannula and said stylet are both retracted; and   switch means for actuating said electronic control means,   wherein said electronic control means includes means for limiting extension of said stylet and cannula by said actuator means to a single forward motion and single rearward motion per actuation of said switch means;   and wherein said position sensing means includes first sensor means for detecting when said cannula reaches said predefined extended position and when said stylet reaches said predefined retracted position, and second means for detecting when said cannula reaches said predefined retracted position, said first and second means for detecting comprising first and second wiperless sensors, respectively.   
     
     
       9. The electronic biopsy instrument of claim 8, wherein said position sensing means includes an optoelectronic sensor. 
     
     
       10. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula;   position sensing means including an optoelectronic sensor for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means, said control means including means responsive to said position sensing means for stopping the motion of said stylet and cannula when said cannula reaches a predefined extended position whereby said cannula and stylet are both extended, when said cannula reaches a predefined retracted position whereby said cannula is retracted and said stylet is extended, and when said stylet reaches a predefined retracted position whereby said cannula and said stylet are both retracted; and   switch means for actuating said electronic control means,   wherein said electronic control means includes means for limiting extension of said stylet and cannula by said actuator means to a single forward motion and single rearward motion per actuation of said switch means;   and wherein said position sensing means includes first means for detecting when said cannula reaches said predefined extended position and when said stylet reaches said predefined retracted position, and second means for detecting when said cannula reaches said predefined retracted position, said first and second means for detecting comprising forst and second optoelectronic sensors, respectively.   
     
     
       11. The electronic biopsy instrument of claim 10, wherein said actuator means includes an electric motor, a drive shaft, and a rotary cam coupled to said drive shaft for translating rotary motion to linear motion, and wherein said position sensing is responsive to the angular position of said rotary cam, said first and second means for detecting including stationary first and second optoisolators, respectively, and a common slotted disc coupled to said drive shaft.   
     
     
       12. The electronic biopsy instrument of claim 11, wherein said cam has an S-curve profile. 
     
     
       13. An electronic biopsy instrument, comprising: a cannula;   a stylet slidably mounted in said cannula;   electromechanical actuator means for producing sequential linear motion of said stylet and cannula, said actuator means including means for extending said stylet and thereafter extending said cannula;   position sensing means for sensing the position of said cannula;   electronic control means connected to said position sensing means for controlling said actuator means; and   switch means for actuating said electronic control means,   wherein said electronic control means includes means for limiting extension of said stylet and cannula by said actuator means to a single forward motion and single rearward motion per actuation of said switch means;   wherein said actuator means includes an electric motor, a drive shaft, and a rotary cam coupled to said drive shaft for translating rotary motion to linear motion,   and wherein said position sensing means includes first and second means for sensing the angular position of said rotary cam said first and second means including first and second optoelectronic sensors, respectively, first and second, respectively, and a common slotted disc coupled to said drive shaft.   
     
     
       14. The electronic biopsy instrument of claim 13, wherein said cam has an S-curve profile.